In an uplink radio access system for next-generation mobile communication, importance is attached to a high transmission power efficiency of mobile stations in order to expand communication areas. For such a system, SC-FDMA having relatively low PAPR (Peak to Average Power Ratio) is believed to be advantageous. Realization of high-speed data transmission is highly required in next-generation mobile communication. However, in an environment where high-speed data transmission is performed using a single carrier (hereinafter, referred to merely as “SC”), there arises a problem of multipath interference, i.e., interference between symbols received by multipath occurs.
A linear equalizer is known as a means for suppressing the multipath interference. Non-Patent Document 1 to be described later has proposed a frequency domain equalizer that performs equalization processing as signal processing in a frequency domain so as to significantly reduce the amount of calculation. A conventional SC receiver performs equalization processing in a frequency domain like a technique disclosed in Non-Patent Document 1, while performs signal processing such as conversion of each user signal into a signal having a carrier center frequency, reception filtering, or channel estimation in a time domain.
On the other hand, an SC-FDMA receiver performs all demodulation processing including channel estimation as well as equalization processing in a frequency domain. Thus, the structure of a receiver can be simplified. Concerning an SC-FDMA receiver, Japan Patent Application No. 2005-280091 discloses a multi-user receiver that applies DFT (Discrete Fourier transform) to SC-FDMA signals all, at once for all users and performs reception filtering, channel estimation, or equalization, processing in a frequency domain.    Non-Patent Document 1: D. Falconer, S. L. Ariyavisitakul, A. Benyamin-Seeyar, and B. Eidson, “Frequency domain equalization for single-carrier broadband wireless access,” IEEE Commun. Mag. vol. 40, no. 4, pp. 58-66, April 2002.